AT&T Galaxy S4 Rooting Question

AT&T Galaxy S4 Rooting Question

I am on ATT and have apparently rooted my phone. There was an apk that I isntalled that did it for me...I got Super User access and what not. Now seeing as how I havent rooted anything since my Droid X. Is there an easy way to flash a rom? I've tried to read the posts on the xda forum but am really confused.